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Developing circadian rhythmicity in infants
1Yale Child Health Research Center, Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut 06510, USA. scott.rivkees@yale.edu
Insights
The infant circadian timing system develops early and responds to light. Early light exposure in premature infants helps establish sleep-wake patterns aligned with the 24-hour light-dark cycle.
Area of Science:
- Neonatal physiology
- Chronobiology
- Developmental neuroscience
Background:
- Circadian rhythms are approximately 24-hour cycles regulated by an internal clock.
- The primate circadian timing system, including the suprachiasmatic nuclei, develops prenatally.
- Infant circadian systems are sensitive to light, even at premature stages.
Purpose of the Study:
- To investigate the development and regulation of the circadian timing system in infants.
- To understand the role of light in modulating the developing circadian clock in premature infants.
- To highlight the significance of circadian biology in neonatal care.
Main Methods:
- Review of recent evidence on prenatal and postnatal development of circadian rhythms in primates.
- Analysis of studies examining light's effect on the premature infant circadian system.
- Observation of rest-activity patterns in response to controlled lighting conditions.
Main Results:
- The circadian timing system is present by midgestation in primates.
- Low-intensity light can effectively regulate the developing circadian clock in premature infants.
- Early exposure to cycled lighting promotes alignment of infant rest-activity with the 24-hour light-dark cycle.
- Mature circadian rhythms in sleep-wake and hormone secretion typically emerge after two months of age.
Conclusions:
- The developing circadian system in infants is responsive to photic cues.
- Early light-based interventions can optimize circadian rhythm development in premature infants.
- Circadian biology is poised to become a critical aspect of neonatal care.
Abstract:
Circadian rhythms are endogenously generated rhythms with a period length of approximately 24 hours. Evidence gathered during the past decade indicates that the circadian timing system develops prenatally and the suprachiasmatic nuclei, the site of a circadian clock, is present by midgestation in primates. Recent evidence also shows that the circadian system of primate infants is responsive to light at very premature stages and that low-intensity lighting can regulate the developing clock. After birth, there is progressive maturation of the circadian system outputs, with pronounced rhythms in sleep-wake and hormone secretion generally developing after 2 months of age. Showing the importance of photic regulation of circadian phase in infants, exposure of premature infants to low-intensity cycled lighting results in the early establishment of rest-activity patterns that are in phase with the 24-hour light-dark cycle. With the continued elucidation of circadian system development and influences on human physiology and illness, it is anticipated that consideration of circadian biology will become an increasingly important component of neonatal care.
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